Charles e



(No Model.)

0. E. SGRIBNER v MULTIPLE SWITGHBOARD SYSTEM FOR TELEPHONE EXCHANGES.

No. 488,036. Patented Dec. 13, 1892, V

L zz zwm 7 y 0m+ (m N KRIS PErER5 cu. PHOTO-LITHQ, WASHINGTON. 0.1:.

UNITED STATES PATENT OFFICE.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE WESTERN ELECTRIC COMPANY, OF SAME PLACE.

MULTIPLE-SWITCHBOARD SYSTEM FOR TELEPHONE-EXCHANGES.

SPECIFICATION forming part of Letters Patent No. 488,036, dated December 13, 1892.

Application filed April 16, 1892. Serial No. 429,488. (No model.)

To all whom it may concern: the spring-jacks of the line, the shunt-circuit Be it known that 1, CHARLES E. SGRIBNER, is closed at the other break, and a subsequent a citizen of the United States, residing at calling-signal from the sub-station causes the Chicago, in the county of Cook and State of electro-magnet to again close the remaining 5 Illinois, have invented a certain new and usebreak of the short-circuit around the annunfulImprovementinlVIultiple-Switchboard Sysciator, thus preventing the operation of the tems forTelephone-Exchanges, (Case No. 303,) annunciator. of which the following is a full, clear, con- In practice I have found it desirable to cise, and exact description, reference being place one pair of contacts upon the annuncito had to the accompanying drawings, forming ator itself, thus making the annunciator pera part of this specification. form the function of the electro-magnetic de- My invention relates to that class of mulvice described. The movable contact-piece tiple-switchboard systems in which the indiupon the annunciator may be carried by an vidual annunciator of a telephone-line is perarmature or the catch-arm thereof, and may r 5 manently connected with the line-circuit. Its be sufficiently flexible to allow motion of the object is to provide means for preventing the armature after the contact-spring is closed operation of the individual annunciator by upon its contact-anvil, the catch of the ansignalingcurrents sent over the line-circuit nunciator which engages with the shutter from either of the connected sub-stations afthereof being made of such length as not to 2o ter a connection has been made to the line. release the shutter until after the points have My invention consists in a normally-open been closed together. Thus when the annunshunt or short circuit about the individual anciator is energized by a calling-current the nunciator of the line and means actuated by first portion of the movement of its armature an electro-magnetic device in the line-circuit closes the two contact-points together, which, z 5 to close the shunt-circuit when signaling-eurif the remainder of the shunt-circuit be comrent is sent over the line-circuit while a conpleted, prevents further operation of the annection exists to the line. nunciator. If the remainder of the shunt-cir- My invention comprises a shunt or short cuit be incomplete,.the armature is further circuit about the individual annunciator norattracted, so as to release the shutter. The 3o mally open at two points, an electro-magnetic remaining break of the shunt-circuit may be device in the line-circuit arranged to close situated upon the spring-jacks, each springone'of the breaks of the shunt-circuit when jack having two contact-pieces, representing actuated, and normally insulated contactthe normally-separated terminalsof the shuntpieces upon the different spring-jacks of the circuit, all the corresponding contact-pieces 3 5 line constituting the terminals of the remainof the spring-jacks being connected together,

ing break of the shunt-circuit, and a contactthe loop-plug or connecting-plug being arpiece upon the loop-plug used in making conranged to cross together the two terminal nection with the line adapted to cross together contact-pieces. I the said contact-pieces, and thus to complete My invention is illustrated in the accomo 40 the shunt-circuit when the plug is inserted panying drawing. Therein I have shown into the spring-jack. In the normal conditwo sub-stations equipped with the ordinary tion of the line the shunt-circuit is, as stated, apparatus, each connected with spring-jacks open at two points. IV hen the call-signal is upon one of two sections of multiple switchsent from the sub-station of the line to the board and with an individual annunciator 5 5 exchange, the shunt-circuit is closed by the upon one of the switchboards. Two cord-cirelectro-magnetthereat at one point, but being cuits or connecting-outfits are shown, one at open at another point does not short-circuit each board, that at one of the boards being the annunciatorfwhich is accordingly opershown in position of connecting the two subated, giving the signal to the attendant. scribers lines and that at theother board be- 50 When, however, a connection has been made ing shown in the act of testing a line to deto line by inserting a loop-plug into one of termine whether it is already in use or not.

of the switch. An earth connection is attached to the branch, including the generator and signal-bell, in order that call-signals may be sent or received either over a metallic circuit made up of the lines 5 b or over a grounded circuit formed of the line b and an earth-return. The lines I) I) extend to the exchange, where they are connected to the linesprings c c of two spring-jacks dd upon two sections of multiple switchboard e c. The spring-jacks d d are of ordinary construction, each having, in addition to the two linesprings c and c, a test-ring f, insulated from the line-springs. The test-ringsffare electrically connected together. The'conduetors Z) I) after passing the different spring-jacks upon the switchboards are connected together through the electro-magnet coil of the individual annunciator g of ordinary construction. Annunciator g is provided, as described, with a flexible contact-springg', carried upon the arm g carrying the catch engaging with the shutter 9 A contact-anvil gtis disposed in proper position to make contact with the spring g when a very slight motion is communicated to the armature g The catch carried by the arm g engaging the shutter 9 is made of such length as not to release the shutter until a movement greater than necessary to close the contacts g g has been given to the armature. The arm g is connected through the pivot supporting the armature with the side b of the line-circuit. The contact-anvil g is connected with the conductor, joining the different test-ringsfof the spring-jacks d cl. The apparatus at the remaining sub-station is of similar character and is connected with similar apparatus at the exchange, ,the annunciator h of the line being, however, placed upon the section 6 of switchboard, so as to be under the care of a different attendant operator.

The operators connecting apparatus is of well-known character. It comprises two loopplugsivlfleach having two contact-pieces, one of which-the tipmakes contact with the shorter line-spring c of the spring-jack into w hich the plug maybeinserted and the otherof which-the slcevemakes contact with both the longer line-spring c and with the test-ring f of the spring-jack. The like contact-pieces of the two plugs of a pair are connected together by conductors lo ringing-keys Z Z being included in the conductor 70, each adapted to disconnect the sleeve of the plug from the conductor 70 and to connect it with one pole of the calling-generator on, whose other pole is grounded when the key is depressed. A listening-key a has its contactsprings connected with the different conductors 7c 70, respectively. Its contact-anvils constitute the terminals of the operators telephone set 0. In order to enable the operator to test any spring-jack to determine whether the line thereof is already in use or not, an induction-coil p is provided, having its sec ondary connected in parallel with the telephone-set 0, its primary being included in a local circuit with a battery (1 and a microphone 4, lightly adjusted and kept in continuous slight vibration. A slight telephonic un= dulatory current is thus induced in the secondary of the coil 19 and normally finds circuit through the operators telephone set 0,

producing a slight rustling noise therein. When the operator desires to test a line to determine whether it is already in use or not, sheinserts one connecting-plug of apairjust so far into thespring-jack to be tested that the tip and sleeve of the plug make contact with the longer line-spring and the test-ring of the spring-jack, respectively, at the same time connecting her telephone set with the plug-circuit and fixing her attention upon the slight noise in the receiver. If the line be not in use, the test-ringfand the line-spring will be insulated from each other and the sound in the telephone will continue uninterrupted; but if the line tested were in use the said contact-pieces would be short-circuited, and would thus short-circuit the secondary of the induction-coil p, completely shunting the current thereof from the telephone-receiver, and hence producing silence therein. silence will be interpreted by the operator making the test to be an indication that the line tested is already in use. A clearing-out annunciator s is included in a branch from the conductor 70 to earth.

When a generator at a sub-station-for example, sub-station 1is operated to send calling-signal to the exchange, the current therefrom flows over the line-circuit b b'the switch-hook a being in its lowest position to the exchange, and there through the electro-magnet coil of the annunciator g of that line. The electro-magnet being energized attracts its armature 9 closing the contacts g 9 together; but since the test-rings fof the spring-jacks of the line are still insulated, the line not being in use, the annunciator is not shunted and continues to actuate the armature until the shutter g is released and falls, indicating the signal to the operator. The operator at board 6 then inserts one plug, as t', of a pair into spring-jack d at her board. The lines I) b from sub-station 1 are thus extended to the conductors 70 7c, and when the operator has depressed the plunger of key 77. to connect her telephone-set to the cord-circuit she is enabled to communicate with the subscriber at station 1 and to receive his order-say for connection with station 2. She

then proceeds to test the line called for in'the manner described, and having found it to be This idle, she inserts the other plug 1; of the pair into the spring-jack d of the line called for at her board. The line-circuit from station 1 is thus farther extended from the conductors k k of the cord-circuit through the plug 2" to the corresponding sides of the line to station 2, the subscribers at stations 1 and 2 being thus looped into a continuous metallic cir-v cuit, which 'may be readily traced. The operator now depresses the key Z, thereby disconnecting the sleeve of the plug 11' from the conductor is and connecting it to one side of the calling-generator, whereby calling-current is sent over the line b to the sub-station 2 and through the signal-bell thereat. When the subscribers have completed their conversation, either of themfor example, that one at station 1may send a clearing-out or disconnection signal to the exchange. A portion of this current will find circuit; to earth at the sub-station and over the line b to the exchange and through the line-spring c of spring-jack d to the sleeve of the plug 1', and thence to the conductor is and through the clearing-out annunciator s to earth, thus operating the clearing-out annunciator and in dicating the signal for disconnection to the operator. Another portion of the calling-current will find circuit over the metallic line b b and through the annunciator g. The armature g of the annunciator will thereby be attracted; but in its first movement will close together the contacts g g, thus completing a short circuit from the line b through the armature g to the contact-point, thence through the contact-points to the test-ring f of springjack d, thence through the sleeve of plug 11 to the line-spring c of the jack, thence to the line b. The annunciator is thereby short-circuited before the catch has been lifted to a sufficient distance to release the shutter, and as long as the current continues will vibrate slightly without releasing the shutter.

As I have before generally mentioned, it may be desirable to employ a separate'electro-magnetic circuit-closer in place of the annunciator, provided with several contactpoints in the same relation to the line-circuit as the annunciator herein. The method of accomplishing the substitution will be obvious to any one skilled in the art, and I do not deem it necessary to describe this modification.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- 1. The combinatiomwith an individual annunciator, of an electro magnetic switch adapted to close the circuit when energized, a shunt or short circuit about the said annunciator normally open at two points, adapted to be closed at one point by the said electro-magnetic switch, and means for closing the short circuit at another point when connection is made with the line, substantially as described.

2. The combination, with a telephone line circuit, of an annunciator included in circuit therewith, an electro-magnetic switch also in circuit between the different sides'of line, adapted to close the-circuit when energized, a shunt or short circuit about the said annunciator normally open at two points, but connected with the said electro-magnetic switch to be closed at one point when said switch is actuated, and means for closing the short circuit at the remaining break when connection is made with the line, substantially as described.

3. The combination, with a telephone-line circuit, of an individual annunciator included therein, contact-points upon said annunciator, adapted to be closed together when the magnet of the annunciator is energized, a shunt or short circuit about the annunciator normally open at two points, connected with the contact-points of said annunciator so as to be closed at one point when said annunciator is energized, and means for closingthe remaining break when connection is established with the line, substantially as described.

4. The combination, with a telephone-line extending from a sub-station to an exchange, of spring-jacks at the exchange, each having two contact-pieces connected with the different sides of the line-circuit, respectively, anda third contact-piece insulated from the said line-contacts, a connecting-plug inserted in the said springjack having two contactpieces, one making contact with one of the line-contacts and the other with the remaining line-contact and the extra contact-piece of the spring-jack, an individual annunciator having its electro-magnet coil included in circuit between the different sides of the linecircuit and provided with contact points adapted to be closed by the first movement of theannunciator, and circuit connections joining one of. the said contact-points with the extra contact-piece upon all the springjacks of the line and the other point with that side of the line-circuit which is not crossed with the said extra contact-piece, substantially as described.

5. The combination, with a telephone-line extending froma sub-station to an exchange, of spring-jacks at the exchange, each having two line-contacts connected with the different sides of the line-circuit, respectively, and a third piece normally insulated from the line-contacts, and an individual annunciator having its coil included in the line-circuit, provided with an armature and with contactpoints adapted to be closed by the first movement of the armature, and an indicator adapted to be actuated by a subsequent movement of the armature, circuit connections joining one of said contact-points with the normally-insulated contact-piece upon the different spring-jacks and joining the remain ing contact-point with one side of the linecircuit, and a connecting-plug inserted into the spring-jack having two contact-pieces, one making contact with that line-contact IIO which is connected with one of the said contact-points and the other to cross together the remaining contact-pieces of the jack, substantially as described.

6. The combination, with a source of calling-current at a sub-station, of the line-circuit extending therefrom to an exchange,

spring-jacks connected with the line-circuit at the exchange, an individual annunciator thereat, a shunt-circuit about said annunciator normally open at two points, contactpoints upon the spring-jacks adapted to close the said shunt-circuit at one point when connection is established with the line, an electro-magnetic device adapted to be actuated by the signaling-current to close the remaining break of the shunt-circuit, substantially as described.

In witness whereof Ihereunto subscribe my name this 10th day of March, A. D. 1892.

CHARLES E. SCRIBNER.

Witnesses:

M. J. TALLETT, GEORGE W. MoMAHoN. 

